Field of Invention
The invention relates to a fan and a manufacturing method thereof and, in particular, to a rotor structure of a fan and a manufacturing method thereof.
Related Art
A rotor is commonly applied to a fan by a rivet bushing method. FIG. 1A is a schematic sectional diagram of a conventional rotor structure, and FIG. 1B is a flow chart of a manufacturing method of the conventional rotor structure. As shown in FIGS. 1A and 1B, the conventional rotor structure 1 includes a shaft 11, a magnetically permeable shell 12 and a copper bushing 13. The conventional manufacturing method includes the step S10 in which the shaft 11 and the copper bushing 13 are connected to each other by interference fit, and thereby the shaft 11 is provided with the copper bushing 13. The step S10 also can be called a copper rivet process. Then, the shaft 11 is riveted to the magnetically permeable shell 12 through the copper bushing 13 (step S12), and in other words, the copper bushing 13 connected to the shaft 11 is riveted to the magnetically permeable shell 12 in this step. Finally, a hub 14 and a plurality of blades 15 are formed on the outer side of the magnetically permeable shell 12 by injection molding (step S14), and the blades 15 are disposed on the periphery of the hub 14.
However, in the step S12 of the manufacturing method of the conventional rotor 1 structure, the copper bushing 13 needs to be compressed to connect to the magnetically permeable shell 12. Therefore, the structural strength and the resistance to shock of the conventional rotor structure 1 are limited in a certain degree. Especially in the case of the heavier conventional rotor 1 bearing larger inertial force during the motion of rotation, thus the structural strength will be overloaded. Therefore, the rivet portion of the conventional rotor 1 may be broken or loosed so that the shaft 11 separates from the magnetically permeable shell 12, resulting in the dangerous situation in usage.
Besides, the copper bushing 13 has a larger weight and the production cost thereof is also relative higher. Furthermore, when the magnetically permeable shell 12 is riveted to the shaft 11 through the copper bushing 13, a precise fit for the magnetically permeable shell 12 and the copper bushing 13 is required. In addition, the assembly error and insufficient connection strength may be caused by the fit condition of the jig and copper bushing 13 during the rivet process (S12).
Therefore, it is an important subject to provide a rotor structure of a fan and a manufacturing method thereof in which the copper bushing and the rivet process for the shaft and copper bushing are omitted so that the manufacturing process is simplified and the structural strength of the rotor structure is increased.